In response to demands for a small-sized and light-weight automobile and an enlarged sitting space in the automobile, electric auxiliary machines around engine have also been reduced in size and used near the engine under high temperatures. A bearing grease needs to exhibit a long bearing lubricity lifetime under such severe high-temperature environments. For this reason, the urea grease is often used as the grease having a long bearing lubricity lifetime at high temperatures. For instance, a grease composition using a diurea compound containing an alicyclic amine as a main component has been proposed (Patent Literature 1).
In consideration of the environments and in request for high accuracy and quietness of the bearing, the grease is required to also have a low-noise performance. As urea grease capable of improving the low-noise performance, for instance, a grease composition using a diurea compound containing an aliphatic amine as a main component has been proposed (Patent Literature 2).